#include "crypto.h"
#include <string.h>

// AES S-box
static const uint8_t sbox[256] = {
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

// AES 逆S-box
static const uint8_t inv_sbox[256] = {
    0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
    0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
    0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
    0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
    0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
    0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
    0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
    0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
    0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
    0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
    0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
    0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
    0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
    0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
    0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};

// 轮常量
static const uint8_t rcon[11] = {
    0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
};

// 辅助函数
static uint8_t gmul(uint8_t a, uint8_t b) {
    uint8_t p = 0;
    uint8_t hi_bit_set;
    for (int i = 0; i < 8; i++) {
        if ((b & 1) != 0) {
            p ^= a;
        }
        hi_bit_set = (uint8_t)(a & 0x80);
        a <<= 1;
        if (hi_bit_set != 0) {
            a ^= 0x1b;
        }
        b >>= 1;
    }
    return p;
}

static void sub_bytes(uint8_t *state) {
    for (int i = 0; i < 16; i++) {
        state[i] = sbox[state[i]];
    }
}

static void inv_sub_bytes(uint8_t *state) {
    for (int i = 0; i < 16; i++) {
        state[i] = inv_sbox[state[i]];
    }
}

static void shift_rows(uint8_t *state) {
    uint8_t temp;
    
    // 第二行左移1位
    temp = state[1];
    state[1] = state[5];
    state[5] = state[9];
    state[9] = state[13];
    state[13] = temp;
    
    // 第三行左移2位
    temp = state[2];
    state[2] = state[10];
    state[10] = temp;
    temp = state[6];
    state[6] = state[14];
    state[14] = temp;
    
    // 第四行左移3位
    temp = state[3];
    state[3] = state[15];
    state[15] = state[11];
    state[11] = state[7];
    state[7] = temp;
}

static void inv_shift_rows(uint8_t *state) {
    uint8_t temp;
    
    // 第二行右移1位
    temp = state[13];
    state[13] = state[9];
    state[9] = state[5];
    state[5] = state[1];
    state[1] = temp;
    
    // 第三行右移2位
    temp = state[2];
    state[2] = state[10];
    state[10] = temp;
    temp = state[6];
    state[6] = state[14];
    state[14] = temp;
    
    // 第四行右移3位
    temp = state[3];
    state[3] = state[7];
    state[7] = state[11];
    state[11] = state[15];
    state[15] = temp;
}

static void mix_columns(uint8_t *state) {
    uint8_t temp[4];
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            temp[j] = state[i * 4 + j];
        }
        state[i * 4 + 0] = gmul(0x02, temp[0]) ^ gmul(0x03, temp[1]) ^ temp[2] ^ temp[3];
        state[i * 4 + 1] = temp[0] ^ gmul(0x02, temp[1]) ^ gmul(0x03, temp[2]) ^ temp[3];
        state[i * 4 + 2] = temp[0] ^ temp[1] ^ gmul(0x02, temp[2]) ^ gmul(0x03, temp[3]);
        state[i * 4 + 3] = gmul(0x03, temp[0]) ^ temp[1] ^ temp[2] ^ gmul(0x02, temp[3]);
    }
}

static void inv_mix_columns(uint8_t *state) {
    uint8_t temp[4];
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            temp[j] = state[i * 4 + j];
        }
        state[i * 4 + 0] = gmul(0x0e, temp[0]) ^ gmul(0x0b, temp[1]) ^ gmul(0x0d, temp[2]) ^ gmul(0x09, temp[3]);
        state[i * 4 + 1] = gmul(0x09, temp[0]) ^ gmul(0x0e, temp[1]) ^ gmul(0x0b, temp[2]) ^ gmul(0x0d, temp[3]);
        state[i * 4 + 2] = gmul(0x0d, temp[0]) ^ gmul(0x09, temp[1]) ^ gmul(0x0e, temp[2]) ^ gmul(0x0b, temp[3]);
        state[i * 4 + 3] = gmul(0x0b, temp[0]) ^ gmul(0x0d, temp[1]) ^ gmul(0x09, temp[2]) ^ gmul(0x0e, temp[3]);
    }
}

static void add_round_key(uint8_t *state, const uint32_t *round_key) {
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            state[i * 4 + j] ^= (round_key[i] >> (24 - j * 8)) & 0xff;
        }
    }
}

static void key_expansion(const uint8_t *key, uint32_t *round_keys, int key_len) {
    int nk = key_len / 4;
    int nr = nk + 6;
    
    // 复制初始密钥
    for (int i = 0; i < nk; i++) {
        round_keys[i] = ((uint32_t)key[4*i] << 24) | ((uint32_t)key[4*i+1] << 16) |
                       ((uint32_t)key[4*i+2] << 8) | ((uint32_t)key[4*i+3]);
    }
    
    // 生成轮密钥
    for (int i = nk; i < 4 * (nr + 1); i++) {
        uint32_t temp = round_keys[i-1];
        if (i % nk == 0) {
            // 循环左移
            temp = ((temp << 8) | (temp >> 24));
            // S-box替换
            temp = ((uint32_t)sbox[(temp >> 24) & 0xff] << 24) |
                   ((uint32_t)sbox[(temp >> 16) & 0xff] << 16) |
                   ((uint32_t)sbox[(temp >> 8) & 0xff] << 8) |
                   ((uint32_t)sbox[temp & 0xff]);
            // 异或轮常量
            temp ^= ((uint32_t)rcon[i/nk] << 24);
        } else if (nk > 6 && i % nk == 4) {
            // 对于256位密钥的特殊情况
            temp = ((uint32_t)sbox[(temp >> 24) & 0xff] << 24) |
                   ((uint32_t)sbox[(temp >> 16) & 0xff] << 16) |
                   ((uint32_t)sbox[(temp >> 8) & 0xff] << 8) |
                   ((uint32_t)sbox[temp & 0xff]);
        }
        round_keys[i] = round_keys[i-nk] ^ temp;
    }
}

int aes_init(aes_ctx_t *ctx, const uint8_t *key, size_t key_len) {
    if (!ctx || !key) return CRYPTO_ERROR_INVALID_PARAM;
    
    if (key_len != AES_KEY_SIZE_128 && key_len != AES_KEY_SIZE_192 && key_len != AES_KEY_SIZE_256) {
        return CRYPTO_ERROR_INVALID_KEY;
    }
    
    ctx->rounds = (key_len / 4) + 6;
    key_expansion(key, ctx->round_keys, key_len);
    
    return CRYPTO_SUCCESS;
}

int aes_encrypt_ecb(aes_ctx_t *ctx, const uint8_t *plaintext, uint8_t *ciphertext) {
    if (!ctx || !plaintext || !ciphertext) return CRYPTO_ERROR_INVALID_PARAM;
    
    uint8_t state[16];
    memcpy(state, plaintext, 16);
    
    // 初始轮密钥加
    add_round_key(state, &ctx->round_keys[0]);
    
    // 主轮
    for (int round = 1; round < ctx->rounds; round++) {
        sub_bytes(state);
        shift_rows(state);
        mix_columns(state);
        add_round_key(state, &ctx->round_keys[round]);
    }
    
    // 最后一轮（不混合列）
    sub_bytes(state);
    shift_rows(state);
    add_round_key(state, &ctx->round_keys[ctx->rounds]);
    
    memcpy(ciphertext, state, 16);
    return CRYPTO_SUCCESS;
}

int aes_decrypt_ecb(aes_ctx_t *ctx, const uint8_t *ciphertext, uint8_t *plaintext) {
    if (!ctx || !ciphertext || !plaintext) return CRYPTO_ERROR_INVALID_PARAM;
    
    uint8_t state[16];
    memcpy(state, ciphertext, 16);
    
    // 初始轮密钥加
    add_round_key(state, &ctx->round_keys[ctx->rounds]);
    
    // 主轮
    for (int round = ctx->rounds - 1; round > 0; round--) {
        inv_shift_rows(state);
        inv_sub_bytes(state);
        add_round_key(state, &ctx->round_keys[round]);
        inv_mix_columns(state);
    }
    
    // 最后一轮
    inv_shift_rows(state);
    inv_sub_bytes(state);
    add_round_key(state, &ctx->round_keys[0]);
    
    memcpy(plaintext, state, 16);
    return CRYPTO_SUCCESS;
}

int aes_encrypt_cbc(aes_ctx_t *ctx, const uint8_t *plaintext, size_t len, 
                   const uint8_t *iv, uint8_t *ciphertext) {
    if (!ctx || !plaintext || !ciphertext || !iv) return CRYPTO_ERROR_INVALID_PARAM;
    if (len % AES_BLOCK_SIZE != 0) return CRYPTO_ERROR_INVALID_PARAM;
    
    uint8_t block[AES_BLOCK_SIZE];
    uint8_t next_iv[AES_BLOCK_SIZE];
    memcpy(next_iv, iv, AES_BLOCK_SIZE);
    
    for (size_t i = 0; i < len; i += AES_BLOCK_SIZE) {
        // 异或明文和IV
        for (int j = 0; j < AES_BLOCK_SIZE; j++) {
            block[j] = plaintext[i + j] ^ next_iv[j];
        }
        
        // 加密
        aes_encrypt_ecb(ctx, block, &ciphertext[i]);
        
        // 更新IV
        memcpy(next_iv, &ciphertext[i], AES_BLOCK_SIZE);
    }
    
    return CRYPTO_SUCCESS;
}

int aes_decrypt_cbc(aes_ctx_t *ctx, const uint8_t *ciphertext, size_t len,
                   const uint8_t *iv, uint8_t *plaintext) {
    if (!ctx || !ciphertext || !plaintext || !iv) return CRYPTO_ERROR_INVALID_PARAM;
    if (len % AES_BLOCK_SIZE != 0) return CRYPTO_ERROR_INVALID_PARAM;
    
    uint8_t block[AES_BLOCK_SIZE];
    uint8_t next_iv[AES_BLOCK_SIZE];
    memcpy(next_iv, iv, AES_BLOCK_SIZE);
    
    for (size_t i = 0; i < len; i += AES_BLOCK_SIZE) {
        // 保存当前密文块作为下一个IV
        memcpy(block, &ciphertext[i], AES_BLOCK_SIZE);
        
        // 解密
        aes_decrypt_ecb(ctx, &ciphertext[i], &plaintext[i]);
        
        // 异或明文和IV
        for (int j = 0; j < AES_BLOCK_SIZE; j++) {
            plaintext[i + j] ^= next_iv[j];
        }
        
        // 更新IV
        memcpy(next_iv, block, AES_BLOCK_SIZE);
    }
    
    return CRYPTO_SUCCESS;
} 